AML1 IN NORMAL AND LEUKEMIC CELLS

正常细胞和白血病细胞中的 AML1

• 批准号: 6595012
• 负责人: JAMES R DOWNING
• 金额: $ 24.14万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6595012
• 关键词: acute leukemia; carcinogenesis; developmental genetics; gene mutation; gene targeting; hematopoiesis; laboratory mouse; neoplasm /cancer genetics; oncoproteins; protein structure function; tissue /cell culture; transcription factor

The AML1/CBFbeta transcription factor complex is one of the most frequent targets of genetic alterations in human acute leukemia, being targeted in up to one-third of acute myeloid and lymphoblastic leukemia by either chromosomal induced rearrangements, or point mutation. Prior work from my laboratory has demonstrated that AMNL1 normally functions as a master regulatory transcriptional switch that is essential for the formation of the definitive hematopoietic systems. In our preliminary data, we now extend this observation to show that AML1/CBFbeta establishes, in a dose-dependent manner, a transcriptional cascade that is required for the formation of definitive hematopoietic stem cells (HSCs) in the aorta-gonad mesonephros region (AGM) of the developing embryo. Moreover, subtle alterations in the level of AML1/CBFbeta induces dramatic changes in the temporal and spatial generation of HSCs, shifting them from their normal position in the AGM to the yolk sac. The initiation of leukemia by chromosomal rearrangement-induced-induced alteration in ABL1/CBFbeta appears to result at least in part, from a partial dominant negative inhibition of normal AML1/CBFbeta, leading to alterations in the self-renewal and maturation of HSCs. Importantly, however, our preliminary data clearly demonstrates that AML1-ETO alone is insufficient to induce leukemia, but rather must cooperate with secondary genetic alterations to transform HSC. Based on these observations, our working hypothesis is that a certain threshold level of AML1/CBFbeta is required for the function of HSC. Genetic changes that decrease the activity of the complex below this level directly alter HSC growth, leading to a pool of "pre-leukemic) cells that must acquire secondary mutations before they can generate a full leukemic phenotype. To directly address this hypothesis, experiments are proposed in Specific Aim 1 that will utilize a conditional AML1-ETO knock in-mouse that was recently generated in my laboratory to define the spectrum of secondary mutations able to cooperate with AML1-ETO to induce leukemia. In Specific Aim 2, we will extend these studies to determine how AML1 mutations identified in familial and sporadic cases of AML predispose to leukemia through the generation of mice containing these mutations in their germline. Together these studies should provide critical insights into the molecular pathology of the core-binding factor leukemia. Moreover, the murine models developed through these efforts should prove to be valuable reagents through which to assess the potential therapeutic use of drugs targeted toward either AML1-ETO or its bound nuclear co-repressors.

AML 1/CBFbeta转录因子复合物是人类急性白血病中遗传改变的最常见靶点之一，通过染色体诱导的重排或点突变靶向多达三分之一的急性髓细胞和淋巴细胞白血病。我实验室之前的工作已经证明，AMNL 1通常作为主转录调节开关发挥作用，这对于最终造血系统的形成至关重要。在我们的初步数据中，我们现在扩展了这一观察结果，以表明AML 1/CBFbeta以剂量依赖性方式建立了一个转录级联反应，该转录级联反应是在发育胚胎的性腺中肾区（AGM）形成永久性造血干细胞（HSC）所必需的。此外，AML 1/CBFbeta水平的细微变化诱导HSC产生的时间和空间发生巨大变化，使它们从AGM中的正常位置转移到卵黄囊中。通过染色体修复诱导的ABL 1/CBF β改变引发白血病似乎至少部分是由于正常AML 1/CBF β的部分显性负抑制，导致HSC自我更新和成熟的改变。然而，重要的是，我们的初步数据清楚地表明，AML 1-ETO单独不足以诱导白血病，而是必须与继发性遗传改变合作来转化HSC。基于这些观察结果，我们的工作假设是，一定的阈值水平的AML 1/CBFbeta的HSC的功能是必需的。将复合物的活性降低到该水平以下的遗传变化直接改变HSC的生长，导致“前白血病”细胞池，其必须获得二次突变才能产生完整的白血病表型。为了直接解决这一假设，在特定目标1中提出了实验，该实验将利用我的实验室最近生成的条件性AML 1-ETO敲入小鼠，以确定能够与AML 1-ETO协同诱导白血病的继发突变谱。在特定目标2中，我们将扩展这些研究，以确定在家族性和散发性AML病例中发现的AML 1突变如何通过在其种系中含有这些突变的小鼠的产生而使白血病易感。总之，这些研究应该提供关键的见解核心结合因子白血病的分子病理学。此外，通过这些努力开发的小鼠模型应被证明是有价值的试剂，通过它来评估针对AML 1-ETO或其结合的核辅阻遏物的药物的潜在治疗用途。